UID Changeable Mifare Ultralight Card.
It can be modified with the Official ACR122U Reader.

MIFARE® Ultralight® Compatible 7-Byte UID Changeable Magic Card

White Card

MIFARE® Ultralight® Compatible 7-Byte UID Changeable Magic Card

(2 Reviews) $4.99 $69.99
MIFARE® Ultralight® Compatible 7-Byte UID Changeable Key Fob

Key Fob

MIFARE® Ultralight® Compatible 7-Byte UID Changeable Key Fob

(2 Reviews) $4.99 $69.99